Is this a normal reaction to laser hair removal? 3 days post op. (photos)

This is a bit of an extreme reaction, but everyone's skin reacts differently to the laser.  I would suggest trying Benadryl to help.  It is just a sign that the laser worked, but sometimes it can be uncomfortable for the patient.  Perhpas trying your next treatment on a lower setting might be better for you.

Thanks for your question and posting pictures.  It's been a couple of days so I'm sure your legs are getting back to normal.  Sometimes this happens on its own, but not normally.  Don't let this dissuade you from doing additional treatments.  After LHR and most other laser treatments, it is important to not raise your body temperature for the next several hours.  Avoid strenuous exercise, hot tubs or even a hot bath for the rest of the day.  Best of luck.